Injection molded abrasive article and process

ABSTRACT

An abrasive article produced by injection molding or the like, utilizing a thermoformable material with abrasive grit and secondary fillers intermixed homogeneously therein.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.732,503, filed Jul. 18, 1991, entitled "Injection Molded Abrasive Pad"which is a continuation-in-part of U.S. application Ser. No. 526,055,filed May 21, 1990, entitled "Flexible One-Piece Diamond Sheet MaterialWith Spaced Apart Abrasive Portions".

BACKGROUND OF THE INVENTION

The present invention relates to thermoformed abrasive articles andprocesses therefor. Still more particularly the present inventionrelates to an abrasive pad or other abrasive articles such as a lappingtool, abrasive wheels and the like which are injection molded.

In the past, the use of abrasive pads, which include abrasive resinoidsegments attached to backing substrates, has been common when polishingstones and marbles and other materials. Because of the relatively thickand non-yielding resinoid segments generally used in these pads, it hasbeen problematic to provide a flexible type abrasive pad using thesetypes of segments. In the past, these segments have been attached tobacking substrates, such as fabrics or the like, utilizing a largenumber of small segments to produce a flexible abrasive pad. Suchabrasive pads are commonly used on rotary polishers for finishing ofmarble floor surfaces, for instance. While these structures have beenuseful as rotary polishing pads, the operational life of the pads hasbeen low. This is because of disattachment of segments during use.

Therefore, it has been a goal in the art to produce a long lastingflexible "segmented-type" abrasive sheet material which will haveincreased durability and be less subject to loss of abrasive portionsduring use. This goal has lead to the discovery that thermoplastics canbe used in abrasive pads as is set forth in my prior patent application,U.S. Ser. No. 526,055, filed May 21, 1990, for "Flexible One-PieceDiamond Sheet Material With Spaced Apart Abrasive Portions" and U.S.Ser. No. 732,503, filed Jul. 18, 1991, entitled "Injection MoldedAbrasive Pad".

It has now been discovered that a broad range of abrasive articles canbe injection molded in an economical and efficient process. In the past,thermosets or thermoset-like materials have primarily been utilized forabrasive articles because of their ability to withstand the hightemperatures associated with abrasive operations. For purposes hereinthermoset refers to polymer materials which chemically cross-link andare not re-workable at substantially the same temperature.

However, the manufacture of abrasive articles with thermoset orthermoset-like materials is costly because of the relatively slow batchtype manufacturing processes and the costs of materials involved. Theuse of an injection molding process with thermosets or thermoplasticshas been thought to be impractical because of the anticipated wear onthe injection molding apparatus. Additionally, some of the extremelyhigh melting point thermoset-like compositions are costly andimpractical for production of abrasive articles.

Therefore, it is a goal in the present invention to provide an abrasivepad which can be efficiently manufactured.

SUMMARY OF THE INVENTION

In accordance with the present invention an abrasive article is producedby injection molding. In accordance with one aspect of the presentinvention there is provided a one-piece flexible abrasive sheet whichmay be in the form of a pad. The one-piece abrasive sheet includes aflexible planar sheet portion having a plurality of abrasive protrusionsextending therefrom. The protrusions are intimately molded with abacking sheet from a thermoplastic material. The material includes anintimate mixture of an abrasive grit material and a thermoplastic.

The abrasive pad of the present invention provides a one-piece pad whichincreases the longevity of the pad during normal use, such as finishingof marble floors or flat edges and radius edges of counter tops, andreduces the amount of lost abrasive portions due to the integral moldingof the portions with the substrate sheet.

In accordance with the methods and products of the present invention avariety of abrasive structures can be produced via injection molding.Additional benefits and advantages of the present invention will becomeapparent from the subsequent description of the preferred embodimentsand the appended claims taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a perspective view of an abrasive pad made in accordance with theteachings of the present invention;

FIG. 2 is a sectional view illustrative of a process, in accordance withthe teachings of the present invention, for manufacture of an abrasivepad;

FIG. 3 is a sectional view of an alternate embodiment of an abrasive padmade in accordance with the teachings of the present invention;

FIG. 4 is a sectional view of the abrasive pad of FIG. 1;

FIG. 5 is a front plan view of an alternate embodiment of an abrasivepad which is injection molded;

FIG. 6 is a rear plan view of the abrasive pad of FIG. 5;

FIG. 7 is a sectional view of the abrasive pad of FIG. 5 taken alongline 7--7;

FIG. 8 is a top perspective view of an abrasive article in the form of alapping tool made in accordance with the teachings of the presentinvention;

FIG. 9 is a bottom perspective view of the abrasive article of FIG. 8;

FIG. 10 is sectional view of the abrasive article of FIG. 8 taken alongline 8--8; and

FIG. 11 is a detailed section taken from area 11 in FIG. 10.

DESCRIPTION OF PREFERRED EMBODIMENTS

In its broadest aspects, the present invention discloses a method andproduct for forming an abrasive article utilizing thermoformingtechniques such as injection molding. Referring now to the drawings,according to the present invention there is provided a flexibleone-piece abrasive sheet, such as pad 10. The one-piece abrasive pad 10includes a flexible planar sheet portion 12 which has a plurality ofabrasive protrusions 14 extending therefrom. The protrusions 14 areintimately molded with the sheet portion 12. In a first preferredembodiment injection molding of a thermoplastic material which has anintimate mixture of an abrasive grit material therein is used. In asecond embodiment a thermosetting material which includes an abrasivegrit material intermixed therein may be used to injection mold abrasivearticles.

In a preferred embodiment of the present invention, the pad 10 is formedin a circular embodiment with a peripheral lip portion 16 extending inthe same direction as the protrusions 14. The lip portion 16advantageously allows the pad to climb over obstacles in an irregularsurface without damaging the abrasive protrusions 14. The advantage ofthe lip portion 16 is set forth in more detail in my co-pending U.S.patent application Ser. No. 502,056 Entitled "Marble, Granite and StoneFinishing Method and Abrasive Pads Therefor", filed Mar. 30, 1990, whichis incorporated herein by reference thereto. The protrusions 14 haveouter abrasive end surfaces 18 which are co-planar to one another.Preferably lip 16 is also co-planar to these peripheral edges 18. Thepad 10 includes a central orifice 20 which is provided for fitting on aparticular rotary tool to provide clearance during use. A means forattachment to a polishing tool, such as a velcro hook and loop fastener21 is attached to the back of the pad 10. Such velcro attachments arecommon in the rotary tools used today. However, other means forattachment could readily be adapted as a particular tool required.

Referring now to FIG. 4, in a preferred embodiment a strengtheningelement 22 is integral with the backing portion 12. The strengtheningelement 22 may be any of a number of materials which have a plurality ofapertures therethrough. A suitable strengthening element providesstrengthening to the pad while retaining flexible characteristics of thebacking portion 12 during use. In a preferred embodiment thestrengthening element 22 is a woven mesh material such as a fiberglassmesh material, as shown in FIG. 4. In the embodiment shown in FIG. 4,the mesh material is embedded in the thermoplastic during the forming ofthe sheet portion 12.

Referring now to FIG. 3, there is shown an alternate embodiment of anabrasive pad, generally shown at 110. In the figures like numeralsdiffering by 100 refer to like elements in the alternate embodiment 110.The alternate embodiment 110 is similar to the embodiment 10, however aperforated phenolic sheet material 124 is utilized as a strengtheningelement in place of the strengthening mesh 22. In this embodiment thethermoplastic is molded in-situ with the phenolic board such that thethermoplastic progresses through the perforations in the phenolic boardmaterial. The phenolic sheet material 124 is attached to thethermoplastic due to the compatible adhesive characteristics of thethermoplastic and the phenolic board and also due to the mechanicalinterlock of the protrusion 114 with the apertures 126 in the phenolicsheet material 124. A NEMA grade G-3 phenolic board, such as thatutilized in circuit board applications, is a preferred material for thisembodiment.

It is critical in a thermoplastic article of the present invention thatthermoplastic materials useful in the present invention are truethermoplastics which may be formed and re-formed at substantially thesame temperature. It is critical in the thermoplastic embodiments of thepresent invention that the working temperature of the thermoplastic begreater than about 100° C. but less than about 250° C. If the workingtemperature drops below the 100° C. temperature the heat created duringuse of the pads will tend to cause plasticity in the materials and causefailures.

In a first preferred embodiment the material used for forming theabrasive articles of the present invention is a true-thermoplasticpolymer material which includes suitable abrasive particles interspersedhomogeneously therethrough. The material used must be sufficientlyformable, by melting, such that it may be forced to flow into and aroundthe strengthening element if desired. Suitable thermoplastic materialsinclude polycarbonates, polypropylenes, polyethylenes, nylons,polyurethanes, or other thermoplastics which can be thermomelted withheat and pressure to produce the abrasive pad 10 or 110. A preferredmaterial is a polypropylene powdered material which may be mixed withdiamond grit particles and/or silicon carbide type particles in itspowdered form prior to the molding operation. Of course, other abrasivegrit materials could be utilized in the present invention as will bereadily appreciated by those skilled in the art.

In the past, it has generally been thought that thermoplastics are notgenerally useful in abrasive grit particles due to the heat producedduring use of abrasive pads, and the resulting decomposition and meltingof such materials. However, in the present invention I have deviatedfrom the prior art teachings by using thermoplastic materials which Ihave found to be suitable for such applications. Thermoplastics aredesirable from a production standpoint in that thermoplastics areadaptable to cost effective manufacturing techniques such as injectionmolding. In a preferred embodiment of the present invention abrasivepads are injection molded in accordance with a process to be set forthbelow.

Referring now to FIG. 2, in accordance with the compression moldingmethod aspects of the present invention a lower mold platen 128 isprovided which has a series of spaced indentation portions 130corresponding to the shape of the desired protrusion in the resultingabrasive pad or sheet, such as sheet 110. An upper platen 132 isprovided for placing a mixture of a thermoplastic material and anabrasive grit material under pressure, in the presence of heat, forforcing the thermoplastic and abrasive grit mixture into theindentations 130 of the mold platen 128. This forms the one-pieceabrasive pad of the present invention.

Thus, in accordance with the steps of the present invention, it is firstnecessary to provide an intimate mixture of abrasive grit materials anda polymer material. This could be accomplished by mixing a powderedthermoplastic with an abrasive grit, by melt mixing these constituents.

Thereafter, this mixture is placed in the mold platen 128 and themixture is heated under pressure to form the resulting article 110 inthe mold portion of the platen 128.

In a preferred embodiment, a strengthening element, such as the phenolicboard material 124, is placed in the platen such that the orifices 126are in the same locations as the indentations 130 of the platen 128.Thereafter, a mixture of a thermoplastic and abrasive material is placedon top of this. The platen 132 is then lowered on the above constituentsin the presence of heat which thermoplastically deforms the plasticmaterial with the abrasive grit intermixed therein and forces it throughthe orifices 126 and into the indentations 130 of the lower platen 128.

In an alternate embodiment, such as that shown in FIG. 4, the fiberglassor other mesh material, which is utilized as a strengthening element,may be placed on the platen 128 and thereafter the thermoplasticmaterial is pressed through the apertures and the strengthening elementto form the final abrasive pad or structure, as shown in FIG. 4.

Referring now to FIGS. 5-7, there is shown an alternate embodiment of apad made in accordance with the teachings of the present inventionwherein injection molding is used to produce the pad 210. The pad 210includes a series of pie slice shaped areas, generally indicated at 212,around the circumference of the pad 210. These areas are separated byradial slotted portions, generally indicated at 214. The pie shapedsegments 212 include a series of flattened stub protrusions 216interspersed amongst these pie shaped areas 212. These protrusions areformed by the mold surfaces of an injection type mold cavityconfiguration. The rear side of the pad 210 includes a hollowed outcircumferential portion 218 which has an inner lip 220 and an outer lip222 which extend axially for supporting the pad on the tool supportstructure. The protrusions 224 are spaced throughout the backside andare at a co-planar level with the axial extending lips 220 and 222 forproviding support throughout the pad area.

In an alternate embodiment of an abrasive pad of the present invention,in order to save grit material the backing substrate may be firstinjection molded with an abrasive free polypropylene and thereafter theabrading protrusions 216 may be injection molded onto the backingsubstrate as a separate function. In such an embodiment, the protrusionswill contain the grit matrix material but will be melt bonded to thebacking substrate which contains no grit material. Since the materialsare identical or at least melt bondable to one another the resulting padis a strong one-piece structure. Thus, in accordance with this aspect,grit material is placed only in the areas required by the abrasiveprotrusions and is not wasted as becoming part of the backing substrateor the like.

In accordance with the broad aspects of the process of the presentinvention, a thermoformable polymer such as a thermoset or thermoplasticand abrasive grit material are provided in an intimate mixture suitablefor injection molding. Thereafter an injection molding apparatus isprovided for thermoforming the abrasive grit and polymer mixture. Theabrasive article is then formed by thermoforming the mixture with theinjection molding apparatus to form the abrasive article. The article isthen allowed to cool to set the abrasive article. The thermoplasticmaterial utilized is preferably a true thermoplastic such as that setforth above, however, in an alternate embodiment a thermoset may beutilized. Apparatus utilized can be conventional extruders, blow moldingequipment or the like. In a particularly preferred embodiment aninjection molding process is used as follows.

In accordance with the injection molding process of the presentinvention, an abrasive article may be made with or without astrengthening element sheet inserted therein by the following steps.First a suitable injection mold structure or cavity is prepared andprovided in which the article shape is set forth in an injection moldmachine. Thereafter, a thermoplastic material, preferably apolypropylene or the like, is mixed with abrasive grit material, forinstance from about 2 micron to about 300 micron sized diamond gritparticulate matter and suitable secondary fillers such as siliconcarbide, aluminum oxide, copper powder, aluminum powder, silicafiberglass or the like if desired. Thereafter, the mixture is molded ata temperature above the softening point of the thermoplastic materialand injected into the mold to produce the thermoplastic one-piece pad.In a preferred embodiment, the thermoplastic preferably has a meltingtemperature above about 100° C. and would be molded at a temperature of440° F. (about 226° C.) using 1,000 psi with 50 pounds of back pressure.It is believed that the clamped cycle time would be an effective timesuch as about 12 seconds.

While diamond grit material is preferred as the primary abrasive gritother diamond hardness abrasive grits can be substituted as will bereadily appreciated to those skilled in the art.

If a strengthening element is desired such an element could be placedinto the mold prior to the injection molding process. This allows formolding of the strengthening element into the pad itself. Similarly, anabrasive structure could be formed on a substrate by injection moldingof the abrasive structure onto the substrate.

Thermoplastics for use in injection molding or pressure forming whichprovide proper structure in the final abrasive structure have thefollowing characteristics. Preferably, the thermoplastics will have asoftening point of greater than 100° C. and preferably less than 250° C.and densities of between 3.0 and 4.92 g/cm² and preferably between 3.0to 4.0. Suitable thermoplastic materials include polypropylenes,polyethylenes, low density polyethylenes, high density polyethylenes,nylons and polycarbonates with melt ranges varying from about 100° C. toabout 250° C. Such abrasive structures must be able to withstand heatgenerated during grinding without deteriorating, thus suitable materialshave melting ranges of from about 100° C. to about 250° C. Suitable lowdensity polyethylenes include Hifax™ types manufactured by Himont.Suitable polypropylenes are those such as Profax™ obtained from Himont.A suitable high density polyethylene is a Paxon™ brand obtained fromAllied Corp. Nylon 66 and Nylon 12 are suitable and Lexan™ polycarbonateobtained from G.E. Plastics is also suitable.

In order to enhance the life of the thermoplastic abrading articles ofthe present invention it is preferable that in addition to diamond gritmaterial, secondary abrasive grit fillers be utilized in thethermoplastic articles of the present invention. Such secondary fillersprovide abrasive to the work surface in areas where diamond grit isabsent thereby enhancing abrasion resistance of the tool and protectingthe diamond grit from premature dislodgement. In a preferred embodiment,such secondary fillers may include abrasives such as silicon carbide,aluminum oxide and corundums as examples or may be selected from fillerssuch as powder metals, powder organic material, powdered inorganicmaterials and mixtures thereof. Preferably, thermoplastic abrasivecompositions include from about 5% to about 80% by volume secondaryfillers; from about 1% to about 20% by volume diamond grit and fromabout 5% to about 20% to about 90% by volume thermoplastic material,which thermoplastic is preferably in the range of from about 20% toabout 60%.

Thus, utilizing these teachings, various abrasive structures can beproduced. For instance, a grinding wheel type abrasive structure can beproduced by first selecting a core structure which is compatible forinjection molding of an abrasive mixed with a thermoplastic as set forthabove. Many other shapes or forms can be produced via the injectionmolding of the abrasive grit intermixed with the thermoplastic. Forinstance, diamond wheels, hand sanding pads, rotary edge polishing pads,lapping tools, or the like are possible as articles of manufacture ofthe present invention.

Referring now to FIGS. 8 through 11, there is shown a cylinder typelapping tool 310 produced in accordance with the teachings of thepresent invention. Lapping tool 310 is a one-piece tool injection moldedin accordance with the teachings of the present invention. Lapping tool310 includes a front face 312 and a back surface 314. The front face 312has a lapping tool curvature for finish grinding of a lens. The backsurface includes structure for attachment to a lapping machine.

Referring to FIGS. 10 and 11, the lapping tool 310 is made of athermoplastic 316 with diamond grit particles 318 and secondary fillerparticles 320 interspersed therethrough.

Lapping tools made in accordance with the teachings of the presentinvention have demonstrated improved finishing of lenses in that theycan rough grind and finish grind lenses using the same tool. Usingconventional procedures such operations require two separate steps.Thus, the lapping tools of the present invention provide an unexpectedbenefit over conventional tools.

Abrasive articles can also be produced in accordance with the presentinvention by injection molding of thermoset plastics which areintermixed with an abrasive grit material for thermoset type injectionmolding. Thermoset articles would be useful with abrasive grit andfiller content set forth above. Of course, as will be readilyappreciated by those skilled in the art, thermoset injection moldingtechniques and equipment must be utilized when producing such abrasivearticles.

Injection molded pads have greater homogeneity in grit distribution dueto the inherent mixing involved during the process and quick settingtimes. Thus, abrasive articles produced in accordance with the injectionmolding teachings have superior abrasive qualities over those producedby other processes.

Further understanding of the present invention may be obtained byreference to the following example which is given as furtherillustration of the present invention and is not to be construed to belimiting to the present invention.

EXAMPLE I

50 grams of polypropylene powder obtained from Himont Corporation ofTroy, Mich., product code number PC 072 PM, having a melt grade of 6 to9, were mixed with 30 grams of a silicon carbide 600 grit abrasivematerial and 15 grams of a diamond 20/40 micron material. The powder andabrasive grit material were mixed and blended to form a congruousintermixed material.

A lower mold platen having a 31/4 inch diameter circular indentationwith indentations therein for forming 1/8 inch diameter and 1/16 inchhigh projections and including mold portions for forming a lip 1/8 inchwide by 1/16 of an inch high was provided. A pin was provided at thecenter of the above mold which is 1/2 inch in diameter for performingthe hole in the resulting abrasive pad.

13 grams of the above mixture was placed around the 1/2 inch pin intothe bottom mold platen. On top of this a 20 mesh fiberglass material,formed 31/4 inches in diameter with a 1/2 inch center hole was placed.Thereafter, a suitable top platen was lowered on the above componentsand heated to 380° F. at 5 tons pressure for six minutes.

The abrasive grit and thermoplastic material melts and flows into themold. The mold was released forming an abrasive pad with a lip portion,co-planar abrasive protrusions having abrasive grit materialinterspersed therein and a fiberglass reinforcement member embeddedtherein. The resulting pad was found to be suitable for floor polishingand edge polishing, railings, headstones, monuments and other marblesand the like.

EXAMPLE II

A mold was prepared wherein a 3.5 inch diameter cavity was made with a45° outer ramp flange 0.156 inches wide and having a 0.875 inch centerhole. One face of the mold is planar and flat but includes surfaces forforming an inner and outer backing lip with six pairs of concentricallyspaced supporting protrusions on the bottom surface and a pad. The upperworking surface includes surfaces for forming a series of 0.05 inchdiameter abrasive protrusions which extend 0.05 inches to 0.06 inches inpie shaped areas which are mounted to a 0.015 inch thick web. Six spacedradially extending surfaces for forming slots in a final pad areequiangularly spaced between these pie shaped areas and are 0.180 incheswide. These are angularly spaced radially from the center hole to theouter edge.

A mixture of 50 grams of a polypropylene powder having product codenumber PC 072 PM, obtained from Himont Corporation of Troy, Mich., whichhas a melt grade of 6 to 9 was mixed with 30 grams of a silicon carbide600 grit abrasive material and 15 grams of a diamond 20/40 micronmaterial.

An injection molding apparatus having three heat zones was utilized. Amold with a heated nozzle and a carbide gate and shut off plunger wereused in an injection molding apparatus having three heat zones. Theabove mixture material is injection molded at a temperature of 440° F.using 1,000 psi and 50 pounds of back pressure. The mold base was watercooled and the clamp to clamp cycle time was about approximately 12seconds. After the molding was completed a pad was removed and was foundto be suitable for long life marble or stone polishing.

EXAMPLE III

A mold was prepared wherein a 3.5 inch diameter cavity was made with a45° outer ramp flange 0.156 inches wide and having a 0.875 inch centerhole. One face of the mold is planar and flat but includes surfaces forforming an inner and outer backing lip with six pairs of concentricallyspaced supporting protrusions on the bottom surface and a pad. The upperworking surface includes surfaces for forming a series of 0.05 inchdiameter abrasive protrusions which extend 0.05 inches to 0.06 inches inpie shaped areas which are mounted to a 0.015 inch thick web. Six spacedradially extending surfaces for forming slots in a final pad areequiangularly spaced between these pie shaped areas and are 0.180 incheswide. These are angularly spaced radially from the center hole to theouter edge.

A mixture of 50 grams of a polypropylene powder having product codenumber PC 072 PM, obtained from Himont Corporation of Troy, Mich., whichhas a melt grade of 6 to 9 was mixed with 30 grams of a silicon carbide600 grit abrasive material and 15 grams of a diamond 20/40 micronmaterial.

An injection molding apparatus having three heat zones was utilized. Amold with a heated nozzle and a carbide gate and shut off plunger wereused in an injection molding apparatus having three heat zones. Theabove mixture material is injection molded at a temperature of 440° F.using 1,500 psi and 1,000 pounds of back pressure. The mold base waswater cooled and the clamp to clamp cycle time was about approximately30 seconds. After the molding was completed a pad was removed and wasfound to be suitable for long life marble or stone polishing.

EXAMPLE IV

Injection molded lens lapping cylinder tools were produced in aconventional injection molding machine as follows.

Introduced into the barrel of the machine was 2200 grams of a mixture of57% by weight polypropylene resin, 29% by weight 3 micron aluminum oxidepowder and 14% by weight grit particles of diamond 600 grit.

The rear heating station of the injection molding machine was maintainedat a temperature of 350° F. The middle heating station was maintained ata temperature of 370° F. The nozzle was maintained at a temperature of410° F. The lapping tools were molded at a temperature of 1000 psi with50 pounds of back pressure and a cycle time of 1:20:00 minutes.

The resultant product were lens lapping cylinder tools weighing 250grams each.

The resulting product was installed on a cylinder lapping machine andfound to be suitable for both fine grinding and polishing. The lappingtool produced was used to fine grind a plastic lens in 1.5 minutes andto polish a plastic lens in 4.0 minutes.

While the above description constitutes the preferred embodiments of thepresent invention, it is to be appreciated that the invention issusceptible to modification, variations and change without departingfrom the proper scope and fair meaning of the accompanying claims.

What is claimed is:
 1. An abrasive article comprising:a molded abradingbody produced from an injection molded polymer material with an abrasivematerial and a secondary filler material interspersed homogeneouslytherethrough said abrading body comprising from about 1 to about 20% byvolume diamond hardness abrasive grit, from about 5 to about 80% byvolume secondary fillers and from about 5 to about 90% by volume of athermoformable polymer selected from the group consisting ofthermoplastic polymers having a softening point temperature greater thanabout 100° C. and less than about 250° C. and thermoset polymers.
 2. Theabrasive article of claim 1 wherein said thermoformable polymer is athermoplastic polymer.
 3. The abrasive article of claim 1 wherein saidthermoformable polymer is a thermoset polymer.
 4. The abrasive articleof claim 2 further comprising a substrate wherein said abrading body isinjection molded thereon.
 5. The abrasive article of claim 2 whereinsaid thermoplastic is polypropylene.
 6. The abrasive article of claim 4wherein said thermoplastic is polypropylene.
 7. The abrasive article ofclaim 1 wherein said abrasive material is diamond grit.
 8. The abrasivearticle of claim 2 wherein said thermoplastic polymer is selected fromthe group consisting of polypropylenes, polyethylenes, nylons,polycarbonates and mixtures thereof.
 9. An abrasive article comprisinganabrasive body produced from a homogeneous composition comprising:fromabout 1% to about 20% by volume diamond grit; from about 5% to about 80%by volume secondary fillers; and from about 5% to about 90% by volume ofa thermoformable polymer, selected from the group consisting ofthermoplastic polymers having a softening point temperature greater thanabout 100° C. and less than about 250° C. and thermoset polymers. 10.The abrasive article of claim 9 wherein said abrasive body is producedby injection molding comprising the steps of formulating a fluid mixtureof said grit, fillers and polymer injecting said fluid mixture into amold and allowing solidification thereby producing said abrasivearticle.
 11. The abrasive article of claim 9 wherein said thermoplasticpolymer is selected from the group consisting of polypropylenes,polyethylenes, nylons, polycarbonates and mixtures thereof.
 12. Theabrasive article of claim 9 wherein the thermoformable polymer is athermoplastic polymer.
 13. The abrasive articles of claim 9 wherein saidsecondary fillers are selected from the group consisting of siliconcarbides, aluminum oxides including corundums, and mixtures thereof. 14.The abrasive article of claim 9 wherein said secondary fillers areselected from the group consisting of powdered organic materials,powdered inorganic materials including powder metals, and mixturesthereof.
 15. The abrasive article of claim 9 wherein said thermoformablepolymer is a thermoset polymer.
 16. A process of manufacture of anabrasive article comprising the steps of:a) providing an injection moldcavity for forming a shaped abrasive article; b) formulating a fluidmixture, said mixture comprising from about 1 to about 20% by volumediamond hardness abrasive grit, from about 5 to about 80% by volumesecondary fillers and from about 5 to about 90% of a thermoformablepolymer selected from the group consisting of thermoplastic polymershaving a softening point temperature greater than about 100° C. and lessthan about 250° C. and thermoset polymers; and c) injection molding thefluid mixture into said injection mold cavity.
 17. The process of claim16 wherein the thermoformable polymer is a thermoplastic polymer. 18.The process of claim 17 wherein said thermoplastic is polypropylene. 19.The process of claim 17 wherein said thermoplastic material is selectedfrom the group consisting of polypropylenes, polyethylenes, nylon,polycarbonates and mixtures thereof.
 20. The process of claim 16 whereinsaid abrasive grit is diamond grit.
 21. The process of claim 16 whereinsaid secondary fillers are selected from the group consisting of siliconcarbides, aluminum oxides including corundums, and mixtures thereof. 22.The process of claim 16 wherein said thermoformable polymer is athermoset polymer.
 23. A process of manufacture of an abrasive articlecomprising the steps of:a) formulating a fluid mixture of athermoformable polymer secondary fillers and an abrasive grit material,wherein said thermoformable polymer is selected from the groupconsisting of thermoplastic polymers having a softening pointtemperature greater than about 100° C. and less than about 250° C. andthermoset polymers; b) providing a suitable apparatus for forming anabrasive article shape; and injection molding the fluid mixture andallowing solidifaction in said apparatus.
 24. The process of claims 23,wherein said thermoformable polymer is a thermoplastic polymer.
 25. Theprocess of claims 23, wherein said thermoformable material is athermoset polymer.